1. Technical Field
The present invention relates generally to a flanged support structure that retains various pipeline control mechanisms without housing them in a pressurized “mother-valve” or fluid-retaining container during their useful life. This structure can support a pipeline control mechanism such as a directional-flow mechanism, an orifice plate/conduit-spacer and/or a protection-screen in fluid-tight arrangement in lines carrying water, sewer, natural gas, or other fluids. The present flange structure can allow such pipeline control mechanisms to be replaced under pressure without first shutting down the line. If a line can be easily depressurized or shut down, this assembly can also aid in quick removal and installation of a pipeline control mechanism by hand.
2. Description of Related Art
A typical repair valve is not a flanged structure that can allow depressurization of the structure surrounding an internal valve. Existing U.S. Pat. Nos. 3,908,691 and 6,983,759 for example provide a “mother-valve” completely encompassing and containing a repairable or removable valve which is submerged in the pipeline fluid during its entire useful life. The valve can include a one-piece manufactured structure to provide a hollow through-passage or hollow interior that extends between first and second ends of the housing of the valve. The first and second ends are threaded, flanged, grooved, weld-ended or otherwise configured so that a user can readily connect each end to a respective one of separate first and second pipeline sections, either directly or via intermediate fittings.
The container that houses the replaceable valve cartridge is built in a way similar to a typical valve, but being a “mother-valve” it encompasses in its pocket a removable internal valve and incorporates features that allow an adaptable isolation gate to perform removal of the pipeline control mechanisms without disruption of system or the pressure from within the pressurized container. More specifically, part of the structure defines an opening that provides access to the pressurized cavity of the “mother-valve” interior. A pipeline control mechanism is removably mounted within that opening in fluid-tight engagement with the “mother-valve” structure. There it functions as means for enabling the user to selectively stop and unstop fluid communications between the first and second pipeline sections.
Known repairable valves cannot easily use off-the-shelf pipeline control mechanisms, actuators and levers without providing complicated fluid-tight seals between the “mother-valve” and the pipeline control mechanism because they are pressurized together. The pipeline control mechanism will either require a custom built bonneted product produced to fit the “mother-valve” or a pressure cover plate that requires a stem packing so a custom extension can be used to operate the pipeline control mechanism within the “mother-valve” and can be operated externally.
Regardless of the particular style of known repair valves, all past mechanisms use a completely pressurized container similar to a bowl in shape to hold the pipeline control mechanism where both are pressurized. This container or valve body remains flooded during its lifetime and cannot be completely depressurized to be cleaned out because the system is fully pressurized at all times.
Corrosion is caused by the existing “mother-valve” being filled with pipeline fluid during its useful life. This body holds particles as well, encouraging corrosion to eat away at the valve body fairly quickly. When a pipeline control mechanism is removed from a “mother-valve”, debris falls into the cavity between the pipeline control mechanism and the “mother-valve,” and upon reinstallation of the pipeline control mechanism the particles can impede proper sealing of the pipeline control mechanism to the “mother-valve”.
Left over particles and corrosion can hinder proper seating of the pipeline control mechanism to the “mother-valve” and make it difficult to replace pipeline control mechanisms under pressure in a fluid-tight manner.
Some pipeline systems can be out of service for short periods of time but then need to be on line again without delay. In that event, when the system can be shut down easily for a few minutes to make repairs or change valves, quick change valves will often leave debris in the “mother-valve.”
Another common problem with known repair valves relates to the procedure of hot tapping. This known operation leaves behind many cuttings or chips created by a hole-saw cutting its way through an existing pipeline and depositing many cuttings within the pressurized vessel. Shavings from the hot tapping operation remain within the pressurized interior of the repair valve cavity especially between the pipeline control mechanism and the “mother-valve”. Debris left in the “mother-valve” can create unsuitable seating of the pipeline control mechanism once installed into position after the hot-tapping procedure is performed, allowing future corrosion from unprotected steel shavings mixed with fluids from the pipeline that are left to sit over time.
Shutting down a pipeline is becoming more difficult with each passing year. When industrial plants must stop production to replace a valve it is costly, and if hospitals and cities require a shut down to repair a valve, customer services are not available during such replacement period. Hospitals and large computer cooling systems are very difficult and costly to shut down due to the nonstop services they perform. Today, pipeline systems also have an inability to shut down caused by the aging of infrastructure and pipeline controls. It is also essential that some pipeline systems remain active, such as in laboratories and nuclear facilities. In addition, the difficulty in disposing of hazardous products used in many pipeline systems creates environmental issues, so shutting down and draining a system can be very difficult and expensive.